Traumatic brain injury (TBI) is a life-threatening condition characterized by internal brain swelling, the degree of which can vary greatly. TBI inflicted by a closed head injury or stroke can result in severe brain swelling requiring surgical intervention. The current surgical procedure to treat TBI involves a two-stage surgery. In the first surgery, decompressive craniectomy (DC) is performed in which a large portion of the calvaria is removed to allow un-impeded brain swelling. The portion of calvarial bone removed is considered a critical size defect, as the bone will not naturally heal by itself. After brain swelling has subsided, a second surgery, termed “cranioplasty,” is performed to close the cranial vault. The average time between DC and cranioplasty has been reported at 80 days, and during this time, the brain is left un-protected. Syndrome of the trephined (SoT), also known as sinking skin flap syndrome, is a severe neurological condition associated with mood changes, fatigue, dizziness, motor skill problems, and concentration issues. The occurrence of SoT has been connected to patients following DC for the treatment of TBI. The cause of SoT has been attributed to various factors such as changing intracranial pressure or physical distortion of the brain from the weight of the scalp. Immediate relief from SoT has been observed directly after cranioplasty, and it is recommended that cranioplasty be performed as soon as clinically possible to mitigate the occurrence of SoT. The current two-stage surgical treatment is non-advantageous, as it prolongs patient recovery by requiring two separate surgeries and potentially results in the neurological condition SoT.
Various research groups have reported new approaches to treat TBI. In one study, the effect of a single-surgical approach combining DC and autologous bone flap cranioplasty was investigated in a pediatric patient population. High complication rates were found. A potential issue with combining DC and cranioplasty in a single surgical intervention is that current methods, such as autologous bone flap cranioplasty, do not allow the brain to swell, as the constructs are rigid bodies. Most research into TBI treatment has focused on methods to improve brain tissue healing or blocking tissue growth to ease the transition between DC and cranioplasty. Currently available commercial products for calvarial bone regeneration are incapable of being used for cranioplasty following DC, as the treatments are unable to regenerate sufficient bone across the critical size defect. Bone cements offer the ability to harden in place after placement, but do not offer the ability to transition into bone. There is currently an unmet need for a material capable of being implemented in a single-surgery to treat TBI that is capable of remaining flexible during brain swelling, then transitioning to bone after brain swelling has ceased. It is to this unmet need and others described below that the present disclosure is directed.